Workbench: Reduce VRAM usage depending on mode

We exploit the fact that we are using the metallic workflow for material
and pass the metallic parameter instead of the specular color.

Pack the front facing bit in the color buffer only for matcap display.

Change buffer formats to use less bytes as possible.

Also don't request buffers that we won't use.

Saved 40MB on 2K screen on StudioLight + Shadows + Specular Lighting.

Includes several cleanups.

1 files changed, 23 insertions, 8 deletions

diff --git a/source/blender/draw/engines/workbench/workbench_materials.c b/source/blender/draw/engines/workbench/workbench_materials.c
index 19fb8efb812..1e969956d77 100644
--- a/source/blender/draw/engines/workbench/workbench_materials.c
+++ b/source/blender/draw/engines/workbench/workbench_materials.c
@@ -14,12 +14,15 @@ void workbench_material_update_data(WORKBENCH_PrivateData *wpd, Object *ob, Mate
 {
 	/* When V3D_SHADING_TEXTURE_COLOR is active, use V3D_SHADING_MATERIAL_COLOR as fallback when no texture could be determined */
 	int color_type = wpd->shading.color_type == V3D_SHADING_TEXTURE_COLOR ? V3D_SHADING_MATERIAL_COLOR : wpd->shading.color_type;
-	copy_v4_fl4(data->diffuse_color, 0.8f, 0.8f, 0.8f, 1.0f);
-	copy_v4_fl4(data->specular_color, 0.05f, 0.05f, 0.05f, 1.0f); /* Dielectric: 5% reflective. */
-	data->roughness = 0.5; /* sqrtf(0.25f); */
+	copy_v3_fl3(data->diffuse_color, 0.8f, 0.8f, 0.8f);
+	copy_v3_v3(data->base_color, data->diffuse_color);
+	copy_v3_fl3(data->specular_color, 0.05f, 0.05f, 0.05f); /* Dielectric: 5% reflective. */
+	data->metallic = 0.0f;
+	data->roughness = 0.5f; /* sqrtf(0.25f); */
 
 	if (color_type == V3D_SHADING_SINGLE_COLOR) {
 		copy_v3_v3(data->diffuse_color, wpd->shading.single_color);
+		copy_v3_v3(data->base_color, data->diffuse_color);
 	}
 	else if (color_type == V3D_SHADING_RANDOM_COLOR) {
 		uint hash = BLI_ghashutil_strhash_p_murmur(ob->id.name);
@@ -30,17 +33,21 @@ void workbench_material_update_data(WORKBENCH_PrivateData *wpd, Object *ob, Mate
 		float hue = BLI_hash_int_01(hash);
 		float hsv[3] = {hue, HSV_SATURATION, HSV_VALUE};
 		hsv_to_rgb_v(hsv, data->diffuse_color);
+		copy_v3_v3(data->base_color, data->diffuse_color);
 	}
 	else {
 		/* V3D_SHADING_MATERIAL_COLOR */
 		if (mat) {
 			if (SPECULAR_HIGHLIGHT_ENABLED(wpd)) {
+				copy_v3_v3(data->base_color, &mat->r);
 				mul_v3_v3fl(data->diffuse_color, &mat->r, 1.0f - mat->metallic);
 				mul_v3_v3fl(data->specular_color, &mat->r, mat->metallic);
 				add_v3_fl(data->specular_color, 0.05f * (1.0f - mat->metallic));
+				data->metallic = mat->metallic;
 				data->roughness = sqrtf(mat->roughness); /* Remap to disney roughness. */
 			}
 			else {
+				copy_v3_v3(data->base_color, &mat->r);
 				copy_v3_v3(data->diffuse_color, &mat->r);
 			}
 		}
@@ -151,18 +158,24 @@ int workbench_material_determine_color_type(WORKBENCH_PrivateData *wpd, Image *i
 }
 
 void workbench_material_shgroup_uniform(
-        WORKBENCH_PrivateData *wpd, DRWShadingGroup *grp, WORKBENCH_MaterialData *material, Object *ob)
+        WORKBENCH_PrivateData *wpd, DRWShadingGroup *grp, WORKBENCH_MaterialData *material, Object *ob,
+        const bool use_metallic)
 {
 	if (workbench_material_determine_color_type(wpd, material->ima, ob) == V3D_SHADING_TEXTURE_COLOR) {
 		GPUTexture *tex = GPU_texture_from_blender(material->ima, NULL, GL_TEXTURE_2D, false, 0.0f);
 		DRW_shgroup_uniform_texture(grp, "image", tex);
 	}
 	else {
-		DRW_shgroup_uniform_vec4(grp, "materialDiffuseColor", material->diffuse_color, 1);
+		DRW_shgroup_uniform_vec3(grp, "materialDiffuseColor", (use_metallic) ? material->base_color : material->diffuse_color, 1);
 	}
 
 	if (SPECULAR_HIGHLIGHT_ENABLED(wpd)) {
-		DRW_shgroup_uniform_vec4(grp, "materialSpecularColor", material->specular_color, 1);
+		if (use_metallic) {
+			DRW_shgroup_uniform_float(grp, "materialMetallic", &material->metallic, 1);
+		}
+		else {
+			DRW_shgroup_uniform_vec3(grp, "materialSpecularColor", material->specular_color, 1);
+		}
 		DRW_shgroup_uniform_float(grp, "materialRoughness", &material->roughness, 1);
 	}
 }
@@ -170,8 +183,10 @@ void workbench_material_shgroup_uniform(
 void workbench_material_copy(WORKBENCH_MaterialData *dest_material, const WORKBENCH_MaterialData *source_material)
 {
 	dest_material->object_id = source_material->object_id;
-	copy_v4_v4(dest_material->diffuse_color, source_material->diffuse_color);
-	copy_v4_v4(dest_material->specular_color, source_material->specular_color);
+	copy_v3_v3(dest_material->base_color, source_material->base_color);
+	copy_v3_v3(dest_material->diffuse_color, source_material->diffuse_color);
+	copy_v3_v3(dest_material->specular_color, source_material->specular_color);
+	dest_material->metallic = source_material->metallic;
 	dest_material->roughness = source_material->roughness;
 	dest_material->ima = source_material->ima;
 }